MADS-box transcription factor Mig1 is required for infectious growth in Magnaporthe grisea
MADS-box transcription factor Mig1 is required for infectious growth in Magnaporthe grisea
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DOI：
10.1128/ec.00009-08
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发表时间：
2008-05-01
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影响因子：
--
通讯作者：
Xu, Jin-Rong
中科院分区：
文献类型：
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作者：
Mehrabi, Rahim;Ding, Shengli;Xu, Jin-Rong
稻瘟病菌是研究真菌-植物互作的模式真菌。有丝分裂原活化蛋白（MAP）激酶基因PMK 1和MPS 1参与了M.稻瘟病菌然而，由这些MAP激酶激活的转录因子没有得到很好的研究。在这项研究中，我们的功能特点的MIG 1基因编码的MADS盒转录因子同源的酿酒酵母Rlm 1。在酵母双杂交试验中，MIG 1与MPS 1相互作用，表明MIG 1可能在MPS 1通路下游发挥作用。mig 1缺失突变体生长速度正常，附着胞黑化，但不致病，不能通过伤口感染水稻叶片。由mig 1突变体形成的附着胞发育了穿透钉和初级感染性菌丝，但活植物细胞内的次级感染性菌丝的进一步分化被阻断。然而，mig 1突变体在热杀死的植物细胞或玻璃纸膜中形成感染性菌丝样结构。在表达MIG 1-GFP融合体的转化体中，在营养菌丝和分生孢子梗中检测不到绿色荧光蛋白（GFP）信号。Mig 1-GFP定位于分生孢子、附着胞和感染性菌丝的细胞核。MADS盒的缺失对MIG 1-GFP融合体的表达和定位没有影响，但消除了其补充mig 1突变体的能力。这些结果表明，MIG 1可能需要克服植物的防御反应和分化的次生感染性菌丝在活的植物细胞。MADS-box结构域对MIG 1的功能是必需的，但其核定位是必需的，这可能与MIG 1在分生孢子形成和植物感染过程中被MPS 1激活有关。
Magnaporthe grisea is a model fungus for studying fungus-plant interactions. Two mitogen-activated protein (MAP) kinase genes, PMK1 and MPS1, have been implicated in regulating plant infection processes in M. grisea. However, transcription factors activated by these MAP kinases are not well studied. In this study we functionally characterized the MIG1 gene that encodes a MADS-box transcription factor homologous to Saccharomyces cerevisiae Rlm1. In yeast two-hybrid assays, MIG1 interacts with MPS1, suggesting that MIG1 may function downstream from the MPS1 pathway. The mig1 deletion mutant had a normal growth rate and formed melanized appressoria, but it was nonpathogenic and failed to infect rice leaves through wounds. Appressoria formed by the mig1 mutant developed penetration pegs and primary infectious hyphae, but further differentiation of the secondary infectious hyphae inside live plant cells was blocked. However, the mig1 mutant formed infectious hypha-like structures in heat-killed plant cells or cellophane membranes. In transformants expressing the MIG1-GFP fusion, green fluorescent protein (GFP) signals were not detectable in vegetative hyphae and conidiophores. Mig1-GFP was localized to nuclei in conidia, appressoria, and infectious hyphae. Deletion of the MADS box had no effect on the expression and localization of the MIG1-GFP fusion but eliminated its ability to complement the mig1 mutant. These results suggest that MIG1 may be required for overcoming plant defense responses and the differentiation of secondary infectious hyphae in live plant cells. The MADS-box domain is essential for the function of MIG1 but dispensable for its nuclear localization, which may be associated with the activation of MIG1 by MPS1 during conidiation and plant infection.